Induction furnace



May s, 1928. 1,6694% J. M. WEED INDUCTION FURNACE Original Filed April 19, 1923 2 Sheets-Sheet 1 Inventor: James m. Weed,

Has Attorney.

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Application filed April 19, 1923, Serial This invention relates to induction furnaccs of the repulsion type such as described in theTians-actions of the American Electrochemical Society, Vol. XLZI, 1922, 5 page 233, in which circulation oi the fluid charge is caused by the electro-magnetic reaction between the primary winding and the secondary current carrying elements of the fluid charge, difierences in fluid ressure between current carrying elements w ich are more and less remote from the primary, resulting from this reaction. being utilized to produce the desired circulation. it is the object of my present invention to provide for a more uniform variation of fluid pressure throughout the secondary, to secure a better power factor and to improve regulability of the 'iurnace. I I

In the constructions shown and described in my prior application, Ser. No. 525.660, filed Dec. 29, 1921, where adjacent surfaces of the primary and secondary are parallel to each other, the difierences in fluid pressure are obtained by a parallel displacement between primary and secondary. For in stance, in the preferred embodiment shown on page 234 of the above article. the primary and secondary are both cylindrical in shape and have a common axis. butnre displaced with respect to one another along the axis, giving maximum pressure at that end of the secondary cylinder which is more remote from-the primary Windingby reason of the other end, which is nearer to the primary. In my present inventionol have provided an improved construction in which the adjacent surfaces of primary and secondary are not parallel, being obtainable without displacement, by making the primary, orsecondary, or both primary and secondary. of a dished or frusto-conical shape. One end of a transverse section of the secondary is more remote from the primary winding than the other by reason of the respective shapes of the primary end secondary. 4

Of the accompanying drawings, Fig. 1 is a vertical section of a preferred form of furn'ece embodying my present invention; Figs. 2 and are similar sections of modifications of the same form of furnace as shown in displacement, and minimum pressure at the the differences in fluid pressure a H r. r u.- c Ne. c3333 Renewed August 32 3; l ttle Fig. 1; Figs. 4, 6 and Lars vertical sections of other embodiments oi hly invention;-

5 is a horizonta section taken thrc the lines 5-50? Referring particularly to 1, the fractory charge container or crucibl furnace embodying my invention is into tuted by interlockingfitted members 2, 3 and 4, surrounded by a heat insulating paci 5 and a. metal frame 6. The zncmbe and 4 may consist of fire clay or of fused magnesite bonded togethe suitable binder, such as magnesium older and are fashioned and fired before assem. in the furnace. A cover 2', a charging door 8, and a spout 9 are provided as The members 2 and 3 are nested together with cemented joints, to provide looped cavity 10 which communicates by conduits l1 and 12, with a reservoir 13 provided by the cylindrical m rober 4- which is lifted and cemented to the member 3. A ma netic core 14 is interlinked with the seco ndary coil 10. A cylindrical primary inducin winding 15 is placed upon the upper leg the core which is threaded through the secondary loop, and is arranged coazrially with the secondary loop 10. A lining 16 for the opening through the crucible member 2 erably is provided to protect the winding 15 in case of a break in the member 2 which would permit the escape of liquid charge. ll: will. be observed that of progressively decreasing thickness, from left to right nlong'its axis, melting the chamber 10 frusto-conical in shape. The p rtion or the liquid charge secondary which is ad jacent to theconduit 12 is nearer to the primary coil than the portion at the opposite end of the section of the secondary, which communicates with the conduit 11-. The pressure at the end of the secondary most remote from the primary being greater than the pressure at the end nearer the primary, the charge is ejected from the sewndery into the reservoir through the channel 11 and a return flow occurs into the secondary through the channel 12. -Due to the grad ual variation of the distance between primary and secondary, the fluid pressure in the secondary 10, caused by electromagnetic repulsion between the primary and secondary;

the member 2 is will have a gradual variation from one end of the secondary to the other. That is, in the furnace shown in Fig. 1, there 18 present during operation a fluid pressure which the di erence in the fluid pressure in opposite ends or the secondary and a movement of the rimary coil to the left will decrease the difierence in pressure between these two regions.

in some cases it is advantageous to make the cavity containing the molten charge constituting the secondary, of uniform diameter and to construct the primary winding of the frustoconical or dished shape, as shown in Fig. 2. The primary winding is here des ignated as 17 to distinguish it from the winding 15 of Fig. 1. i

In the construction shown in Fig. 3, both the secondary 18 and the primary 19 are made of irusto-conical shape, the wider ends of the two cones facing in opposite directions. In the modification shown in Fig. 2 the pressure will be maximum at the left side of the secondary 20 which is furthest away from the primary and theilow of liq uid charge will occur through the channel 21 returning through the channel 22. the modification shownin Fig. 3 the flow will occur in the opposite direction, that is, from the channel 23 back through the chan nel 24. v

in the modification of my invention shown in Figs. 4 and 5, the primary winding 25 is disc-shaped while the secondary 26 is frusto-conical or Y dished in shape. The complete circuit current-carrying elements of'the secondary 26 adjacent to its inner periphery are more remote from the primary than those adjacent to the outer periphery. Maximum fluid pressure, therefore, is set up at the inner periphery with a flow from the secondary at27 through the conduit 30 into the reservoir 31 accompanied by a return flow through the conduit 32 into the secondany at its outer periphery at 28.

In the modification shown in Fig. 7, the secondary 33 is disc-shaped, and the primary 34 is frusto-conical in shape. In this-case the outer peripheral portion of the secondary 33 is further away from the primary than the inner peripheral portion; thereby producing a flow upwardly through the conduit 35 into the reservoir 36 accompanied by return flow through the conduit 37.

In the modification shown in Fig. ti both the primary inducing Winding 38 and the secondar 39 are dished in a direction away from eac other so that a maximum pressure is set up at the inner peripheryof the secondary, causing a discharge of fluid through of charge external to said secondar ocales the conduit 40 and a return flow from the reservoir 41 into the secondary 39 through the conduit 4-2.

In each of the modifications shown and described, it will be seen that the secondary may be divided by imaginary surfaces, parallel to the direction of flow of secondary current, into complete circuit current-carrying elements or parts, of varying inductive relationships with the primary, with provision for direct communication between a part of relatively high inductive relationship and an auxiliary charge containing reservoir, and also between a part of relatively low inductive relationship and the reservoir. A circulation of charge, from the part of the secondary of lower inductive relationship to the reservior, returning from the reservoir to the part of higher inductive relationship, is 1 generated by a difference in fluid pressure due to the electromagnetic repulsion between primary and secondary, this fluid pressure being greater for those parts of the second ary which are-in lower inductive relationship with the primary.

What I claim asnew and desire to secure by Letters Patent of the United States is 1. An induction furnace comprising a primary winding, a refractory receptacle providing a looped cavity adapted to contain a liquid charge constituting a secondary the primary and secondary being structurally so related that the spacing from the primary of sections of the secondary in planes passing through the axis of the primary inice creases progressively from one end of the sections to the other, and a passage external to said secondary through which charge may circulate between portions of the secondary spaced dilierent distances from the primary.

2 An induction furnace comprising a magnetic core, a primary winding interlinked therewith, refractory walls providing a cavity adapted to contain a molten charge which constitutes a secondary. said primary 0 and secondary being arranged substantially coaxial with respect to said core and being so shaped that their adjoining sides'are diverging, and means for permitting the flpw tween regions of the secondary space different distances from the primary' An induction furnace comprising a core, a primary winding. a looped cavity for containing a molten charge constituting a mo secondary in inductive relationship with the primary, the primary or secondary being of frusto-conical form, and structurally so related to each other that their adjacent surfaces are diverging, and a conduit-external tosaid cavity between regions spaceddifferent distances from the primary.

4. An induction furnace comprising a;

primary winding, refractory walls providing a looped cavity adapted to contain a gap chargeinterlinked as a secondary with said primary, one of said primary and secondary being cylindrical and the other frusto-conical, and means external to said secondar for conveying charge between regions 0 the secondary spaced apart difierent distances from the primary.

5. An induction furnace comprising a magnetic core, a primary coil, a refractory container providing a cavity interlinked with said primary coil and adapted to contain a charge constituting a secondary coil, said coils being arranged coaxially. and being so shaped that their adjoining surfaces diverge along their common axis, and means for conveyin charge between regions of the secondary W ich are spaced different distances from the primary.

' 6. An induction furnace comprising a core, a primary winding thereon. a furnace structure having refractory walls providing a cavity adapted to contain a fluid secondary magnetically interlinked with said'primary,v at least one of primary and second;- ary havinga frusto-conical shape thereby providinga progressively increasing spac ing from one end of a transverse section thereof to the other, a reservoir. and conduits communicating between said reservoir and'difi'erent regions of said cavity which are spaced unequally from the primary in which a difference of fluid pressure exists by electromagnetic repulsion.

7. An induction furnace comprising a.

core, a primary Windingand a recestacle for containing charge, said receptame ineluding a reservoir and communicating therewith, a looped cavity Within which a. portion of the charge constitutes a closed secondary, at least one of said elements being frusto-conical in silage, said elements being structurally so related that the surfaces of the primary and secondary which are adjacent to eachother are diverging, so that the distance from the primary to the secondary varies gradually from one end to the other of an 0 long transverse mtion of the secondary, and conduits between the secondary cavity and the reservoir whereb fluid charge can flow from the end of sucn transverse sectionsof the secondary cavity, which is more remotejrorn the primary to the reservoir, and memo from the reservoir to the end of the'secondary which is closer,

to the primary.

In witness whereof E have hereunto set my hand this 18th day of Ara-ii, 1923.

JAMES M. WEED. 

